Many folding tools utilize a locking mechanism that prevents the implement from opening and/or closing unintentionally. For example, existing locking mechanisms for folding knives include “back locks” and “liner locks”. The back lock utilizes a generally metallic member that rides on the back of the blade as the blade rotates between a closed position and an open position. Once the blade is in an open position, the back lock member pivots into place behind a flat portion of the tang of the blade, thereby preventing closure of the blade until the back lock member is manually pivoted out of the way of the blade. The liner lock utilizes a thin, generally metallic liner that springs into place behind a flat portion of the tang of the blade, thereby preventing closure until the liner is manually moved out of the way of the blade. In some situations, the back lock and the liner lock have proven to be unreliable. For example, extended use of the back lock and the liner lock, especially in harsh environments, can result in corrosion and wear issues. An example of a liner lock is discussed in U.S. Pat. No. 8,042,276, which is hereby incorporated by reference in its entirety.
As an alternative to the back lock and the liner lock, some lock mechanisms utilize a push button as a lock. To bias the push button into a locked position, a compression spring is positioned coaxially with the pivot axis between the push button and the handle of the folding knife. The addition of a compression spring increases the number of components associated with the locking mechanism, which increases the likelihood of problems. In addition, to accommodate the lack of space between the push button and the handle, a recess is typically formed in the end of the button to at least partially house the compression spring. The recess formed in the button weakens the lock mechanism as the hollow portion of the button typically interacts with the tang of the blade to lock the rotation of the blade. To further accommodate the compression spring, a recess may be formed in the handle as well. However, a recess formed in the handle cannot extend through the handle because the handle acts as a reacting surface for the compression spring. Thus, the handle encloses the locking mechanism and traps water and/or debris within the critical moving parts of the folding knife, which may include the locking mechanism and the pivot axis of the blade. In many situations, trapped water and/or debris can result in corrosion and interfere with the operation of the knife. This problem is accentuated when the folding knife is exposed to harsh environments, including underwater applications.
Based upon at least the aforementioned problems, there exists a long-felt and unsolved need to provide a folding tool with a strong lock mechanism that reduces the number of components utilized in the locking mechanism and that allows drainage of water and/or removal of debris from the critical moving parts of the tool, including the locking mechanism.